American Superconductor Corporation

American Superconducting Corporation

Calman Gold

Otward M Mueller

Ellery F Schempp

Gregory L Snitchler

Bruce B Gamble

Carl J Russo

Richard J Gran

An exciter assembly supplies current to a superconducting load. The exciter assembly includes a transformer for generating the current and an optical emitter and an optical receiver. The transformer includes a stationary winding portion having a stationary winding and a rotatable winding portion having a rotatable winding that outputs the current for the superconducting load. The optical emitter and the optical receiver define an optical path over which information is exchanged between the stationary winding portion and the rotatable winding portion.

Exciter assembly telemetry

An exciter assembly for supplying power to a superconducting load, such as a superconducting field coil, disposed within a cryogenic region of a rotating machine. The exciter assembly provides an efficient and reliable approach for transferring the electrical power energy across a rotating interface and for controlling the ramp up and regulation of field excitation current in the field coil. In particular, the invention provides a controlled recirculation path for current flowing through the field coil. The exciter assembly includes a transformer having a primary winding and a secondary winding, a sensor which provides a control signal indicative of the flow of field excitation current to the superconducting load; and a current regulator which is disposed in the rotating reference frame and, on the basis of the control signal, regulates the field excitation current to a predetermined set. One of the primary and secondary windings is positioned in a rotational reference frame relative to the other of the primary and secondary windings.

Exciter and electronic regulator for rotating machinery

Methods and apparatus for cooling systems for cryogenic power conversion electronics are provided. The invention includes systems having electronic power conversion apparatus comprising at least one cryogenically operated semiconductor switch and at least one cryogenically operated capacitor and cooling means for cryogenically cooling the at least one cryogenically operated semiconductor switch and the at least one cryogenically operated capacitor to a temperature between 90K to 236K. The systems can also include input/output means for supplying power to said power conversion apparatus and receiving power from said power conversion apparatus. In alternative embodiments, liquid cryogens can be used in heat exchange systems in conjunction with refrigeration cold heads or heat pipes. In these embodiments, the cryogen can be recondensed if boiled.

Methods and apparatus for cooling systems for cryogenic power conversion electronics

An electronic power conversion circuit includes cryogenically cooled MOSFET power switching devices arranged in a switch-mode configuration and responsive to control signals for reducing capacitive discharge and commutation losses in the circuit by controlling the period between switch-on and switch-off time (i.e., &ldquo;deadtime&rdquo;) of the MOSFET devices. When one of the MOSFET devices of the circuit is switched off, the opposing MOSFET, after the short deadtime period, is switched on to serve as a commutating device rather, than the opposing MOSFET's intrinsic drain-source diode. The power conversion circuit may include a half-bridge circuit or combinations thereof.

Cryogenically-cooled switching circuit

The invention provides an apparatus for supplying power to superconducting loads includes a current source, a cryogenic region (e.g., a cryogenic chamber), a first switching device in series between the current source and a superconducting load, and a second switching device in parallel with the superconducting load. The switching devices are arranged so that, when the first is closed and the second is open, recharging current is supplied to the superconducting load. The second switching device serves as a shunt. When it is closed and the first is open, current recirculates through the persistent (or partially persistent) superconducting load. The invention also provides a superconducting magnet incorporating such a power supply.

Superconducting magnets and power supplies for superconducting devices

The invention is an inductive device featuring very low losses even in circuits which supply more than about 10 kilowatts of power. The device includes an inductor comprising a core consisting primarily of a highly permeable magnetic material and at least one winding of a high temperature superconducting conductor contained substantially within the core and in spaced relation with respect to the core sufficient to maintain its electrical integrity, refrigeration means for cryogenically cooling at least the conductor winding portion of the inductor to a temperature at which each conductor winding exhibits superconductivity, and input/output means for providing power to and receiving power from each conductor winding. Also disclosed are a balancing choke and a circuit embodying a common mode inductor made in accordance with the invention.

Superconducting inductors

Methods and apparatus for cooling systems for cryogenic power conversion

A control circuit generates signals for controlling the sequence in which selected input signals are carried across the terminals of a polyphase switching conversion circuit. The control circuit includes switching elements galvanically isolated from the selected input signals with the control signals electrically isolated from the switching devices. The control circuit for the conversion circuit is, in essence, electrically isolated from the conversion circuit. The control circuit is configured to have a topology analogous to that of the switching converter and includes conventional switching diodes as well as a light generating device optically coupled to a light sensor which, in response to detection of light from the optically coupled light generating device, provides a control signal to a corresponding switching device. The control circuit also includes a source of regulated and electrically isolated power to operate drive circuitry for the switching devices. The cryogenically cooled switching converter is used to rectify AC input signals generated by a number of variable speed wind-driven turbines, into a DC output signal which can be re-converted into a fixed frequency AC signal, stored, or conveyed via a cryogenically cooled superconducting line to a remote location. A power generation system includes cryogenically cooled power conversion circuitry for converting alternating current (AC) input signals which have naturally occurring, fluctuating frequency characteristics, into a direct current output signal. The control circuit, described above, may be used to control the power conversion circuitry.

Control circuit for cryogenically-cooled power electronics employed in

Methods and apparatus for uninterruptible power supply (UPS) systems are provided. The UPS systems are configured to provide the advantages of an in-line device, and operate in a quasi-standby mode. The UPS includes a rectifier unit and inverter arranged to nominally deliver a portion (e.g. up to about 20%) of the primary AC power supply to a critical load through an output transformer. The rectifier unit preferably includes internal energy storage capabilities, such as a capacitor and inductor. The remaining portion of the AC power supply is nominally supplied directly to the critical load and is controlled by a transfer switch and the output transformer. When a fault is detected in the main AC power supply, the transfer switch switches to a faulted position and power is supplied from the rectifier inductor and capacitor or from a battery to the load through the inverter. Electronic switches such as MOSFETs are provided in the system to control the supply of power from the battery (or other energy storage device) to the inverter and to control the charging and discharging of the battery. The inverter and MOSFETs are designed to withstand transient overpower and overcurrent operation without deleterious consequences by liquid cooling the inverter or the inverter and the MOSFETs under predetermined conditions to temperatures between about 60 K and 270 K.

Uninterruptible power supplies having cooled components

A cryogenically cooled circuit, operating at temperatures at which inductors windings of the circuit exhibit superconducting characteristics, provides unique advantages in high performance, preferably high power circuits. Portions of the circuit (or the entire circuit), as opposed to, for example only the superconducting elements (i.e., inductor winding), are refrigerated to cryogenic temperatures. Advantages in the characteristics of not only the superconducting based components but also the diodes, and gating elements such as MOSFET's, yield a uniquely advantageous circuit enabling the operation of, for example, a switching power supplies, frequency converters, and motor speed controllers with increased performance and efficiency. Size, component count, and stability are benefits attained by cryogenically cooling the entire circuit configuration. Cryogenically-cooled solid-state contacting switches may be utilized for connecting/disconnecting AC and/or DC power between the high performance circuit and a source/load.

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Londonderry, NH, United States of America

Calman Gold